RRC ID 39621
Author Tauchi H, Komatsu K, Ishizaki K, Yatagai F, Kato T.
Title Mutation spectrum of MSH3-deficient HHUA/chr.2 cells reflects in vivo activity of the MSH3 gene product in mismatch repair.
Journal Mutat. Res.
Abstract The endometrial tumor cell line HHUA carries mutations in two mismatch repair (MMR) genes MSH3 and MSH6. We have established an MSH3-deficient HHUA/chr.2 cell line by introducing human chromosome 2, which carries wild-type MSH6 and MSH2 genes, to HHUA cells. Introduction of chromosome 2 to HHUA cells partially restored G:G MMR activity to the cell extract and reduced the frequency of mutation at the hypoxanthine-guanine phosphoribosyltransferase (hprt*) locus to about 3% that of the parental HHUA cells, which is five-fold the frequency in MMR-proficient cells, indicating that the residual mutator activity in HHUA/chr.2 is due to an MSH3-deficiency in these cells. The spectrum of mutations occurring at the HPRT locus of HHUA/chr.2 was determined with 71 spontaneous 6TG(r) clones. Base substitutions and +/-1 bp frameshifts were the major mutational events constituting, respectively, 54% and 42% of the total mutations, and more than 70% of them occurred at A:T sites. A possible explanation for the apparent bias of mutations to A:T sites in HHUA/chr.2 is haploinsufficiency of the MSH6 gene on the transferred chromosome 2. Comparison of the mutation spectra of HHUA/chr.2 with that of the MSH6-deficient HCT-15 cell line [S. Ohzeki, A. Tachibana, K. Tatsumi, T. Kato, Carcinogenesis 18 (1997) 1127-1133.] suggests that in vivo the MutSalpha (MSH2:MSH6) efficiently repairs both mismatch and unpaired extrahelical bases, whereas MutSbeta (MSH2:MSH3) efficiently repairs extrahelical bases and repairs mismatch bases to a limited extent.
Volume 447(2)
Pages 155-64
Published 2000-2-14
DOI 10.1016/s0027-5107(99)00199-2
PII S0027-5107(99)00199-2
PMID 10751599
MeSH Amino Acid Substitution Animals Base Pair Mismatch / genetics* Base Sequence Chromosomes, Human, Pair 2 / genetics DNA Mutational Analysis DNA Repair / genetics* DNA-Binding Proteins / deficiency* DNA-Binding Proteins / genetics Frameshift Mutation Humans Hybrid Cells Hypoxanthine Phosphoribosyltransferase / genetics Multidrug Resistance-Associated Proteins* MutS Homolog 3 Protein Mutagenesis, Insertional Mutation Point Mutation Sequence Deletion Tumor Cells, Cultured
IF 2.398
Times Cited 4
Human and Animal Cells